Porous alumina templates for electronic packages

ABSTRACT

Interposers and methods of making the same are disclosed herein. In one embodiment, an interposer includes a region having first and second oppositely facing surfaces and a plurality of pores, each pore extending in a first direction from the first surface towards the second surface, wherein alumina extends along a wall of each pore; a plurality of electrically conductive connection elements extending in the first direction, consisting essentially of aluminum and being electrically isolated from one another by at least the alumina; a first conductive path provided at the first surface for connection with a first component external to the interposer; and a second conductive path provided at the second surface for connection with a second component external to the interposer, wherein the first and second conductive paths are electrically connected through at least some of the connection elements.

FIELD OF THE INVENTION

The present application describes an interposer such as that which canbe incorporated into a microelectronic assembly which may include anunpackaged semiconductor die or packaged semiconductor die, as well asmethods for making such interposer, which include alumina and/oraluminum features.

BACKGROUND OF THE INVENTION

Microelectronic devices such as semiconductor chips typically requiremany input and output connections to other electronic components. Theinput and output contacts of a semiconductor chip or other comparabledevice are generally disposed in grid-like patterns that substantiallycover a surface of the device (commonly referred to as an “area array”)or in elongated rows which may extend parallel to and adjacent each edgeof the device's front surface, or in the center of the front surface.Typically, devices such as chips must be physically mounted on asubstrate such as a printed circuit board, and the contacts of thedevice must be electrically connected to electrically conductivefeatures of the circuit board.

Semiconductor chips are commonly provided in packages that facilitatehandling of the chip during manufacture and during mounting of the chipon an external substrate such as a circuit board or other circuit panel.For example, many semiconductor chips are provided in packages suitablefor surface mounting. Numerous packages of this general type have beenproposed for various applications. Most commonly, such packages includea dielectric element, commonly referred to as a “chip carrier” withterminals formed as plated or etched metallic structures on thedielectric. These terminals typically are connected to the contacts ofthe chip itself by features such as thin traces extending along the chipcarrier itself and by fine leads or wires extending between the contactsof the chip and the terminals or traces. In a surface mountingoperation, the package is placed onto a circuit board so that eachterminal on the package is aligned with a corresponding contact pad onthe circuit board. Solder or other bonding material is provided betweenthe terminals and the contact pads. The package can be permanentlybonded in place by heating the assembly so as to melt or “reflow” thesolder or otherwise activate the bonding material.

Many packages include solder masses in the form of solder balls,typically about 0.1 mm and about 0.8 mm (5 and mils) in diameter,attached to the terminals of the package. A package having an array ofsolder balls projecting from its bottom surface is commonly referred toas a ball grid array or “BGA” package. Other packages, referred to asland grid array or “LGA” packages are secured to the substrate by thinlayers or lands formed from solder. Packages of this type can be quitecompact. Certain packages, commonly referred to as “chip scalepackages,” occupy an area of the circuit board equal to, or onlyslightly larger than, the area of the device incorporated in thepackage. This is advantageous in that it reduces the overall size of theassembly and permits the use of short interconnections between variousdevices on the substrate, which in turn limits signal propagation timebetween devices and thus facilitates operation of the assembly at highspeeds.

An interposer can be provided as an interconnection element havingcontacts and top and bottom surfaces thereof electrically connected withone or more packaged or unpackaged semiconductor dies at one of the topor bottom surface thereof, and electrically connected with anothercomponent at the other one of the top or bottom surfaces. The othercomponent may in some cases be a package substrate which in turn may beelectrically connected with another component which may be or mayinclude a circuit panel.

Despite all of the above-described advances in the art, still furtherimprovements in interposers and methods of making interposers would bedesirable.

BRIEF SUMMARY OF THE INVENTION

Interposers and methods of making the same are disclosed herein.

In one embodiment, an interposer comprises a region having first andsecond oppositely facing surfaces and a plurality of pores, each poreextending in a first direction from the first surface towards the secondsurface. Alumina may extend along a wall of each pore. A plurality ofelectrically conductive connection elements can extend in the firstdirection, the connection elements consisting essentially of aluminumand being electrically isolated from one another by at least the aluminaextending along the walls of the pores. The interposer may include afirst conductive path provided at the first surface for connection witha first component external to the interposer. The interposer may includea second conductive path provided at the second surface for connectionwith a second component external to the interposer. In one example, thefirst and second conductive paths are electrically connected through atleast some of the connection elements.

In one embodiment, each pore may have a diameter of less than about 2micrometers.

In one embodiment, the first and second conductive paths may be at leastone of a plurality of contacts or a redistribution layer (RDL).

In one embodiment, the first conductive path may comprise a plurality offirst contacts adjacent to the first surface for connection with a firstcomponent external to the interposer.

In one embodiment, the second conductive path may comprise a pluralityof second contacts adjacent to the second surface for connection with asecond component external to the interposer. In one example, at leastsome of the first contacts may be electrically connected with at leastsome corresponding second contacts through the connection elements.

In one embodiment, at least a portion of the interposer may have a heatspreader function.

In one embodiment, the interposer further comprises an aluminum regionsurrounding at least some of the connection elements and configured toprovide a heat spreader function.

In one embodiment, at least some of the first conductive path mayoverlie some of the pores.

In one embodiment, no portion of the at least some first conductive pathmay overlie the connection elements.

In one embodiment, at least some of the first conductive path may bealigned with the connection elements.

In one embodiment, at least some of the pores may be disposed adjacentone another in annular patterns, and at least some of the annularpatterns may encompass connection elements of the plurality ofconnection elements and the alumina extending along the walls of thepores of the at least some annular patterns electrically isolatesrespective connection elements from one another.

In one embodiment, at least some of the pores may incorporate voids.

In one embodiment, at least one connection element may occupy an area ofthe first surface which encompasses areas occupied by others of theconnection elements, the at least one connection element configured as aheat spreader of the interposer.

In one embodiment, at least some of the pores may be at least partiallyfilled with a dielectric material overlying the alumina.

In one embodiment, at least some of the pores may be at least partiallyfilled with an electrically conductive material.

In one embodiment, the interposer comprises second connection elementsextending in the first direction, each second connection elementcomprising an electrically conductive material extending within some ofthe plurality of pores, at least some of the first contacts beingelectrically connected with corresponding second contacts through thesecond connection elements.

In one embodiment, an interposer may comprises a region having first andsecond oppositely facing surfaces and a plurality of pores eachextending in a first direction from the first surface towards the secondsurface. Alumina may extend along a wall of the each pore. A pluralityof connection elements can extend in the first direction and be formedin some of the plurality of pores. Each connection element can comprisean electrically conductive material extending into one pore, theconnection elements being electrically isolated from one another by atleast the alumina extending along the walls of the pores. The interposermay include a first conductive path provided at the first surface forconnection with a first component external to the interposer. Theinterposer may include a second conductive path provided at the secondsurface for connection with a second component external to theinterposer. In one example, the first and second conductive paths may beelectrically connected through at least some of the connection elements.

In one embodiment, each pore may have a diameter of less than 2micrometers.

In one embodiment, the first and second conductive paths may be at leastone of a plurality of contacts or a redistribution layer (RDL).

In one embodiment, the first conductive path may comprise a plurality offirst contacts adjacent to the first surface for connection with a firstcomponent external to the interposer.

In one embodiment, the second conductive path may comprise a pluralityof second contacts adjacent to the second surface for connection with asecond component external to the interposer. In one example, at leastsome of the first contacts are electrically connected with at least somecorresponding second contacts through the connection elements.

In one embodiment, at least some of the first conductive path mayoverlie some of the pores that do not include connection elements formedtherein.

In one embodiment, no portion of the at least some of the firstconductive path may overlie the connection elements.

In one embodiment, at least some of the first conductive path may bealigned with the connection elements.

In one embodiment, at least some of the pores may incorporate voids.

In one embodiment, some connection elements occupies an area of thefirst surface which encompasses areas occupied by others of theconnection elements, the some connection elements configured as a heatspreader of the interposer.

In one embodiment, at least some of the remaining pores may be at leastpartially filled with a dielectric material overlying the alumina.

In one embodiment, at least some of the remaining pores may be at leastpartially filled with an electrically conductive material.

In one embodiment, a method of fabricating an interposer comprisesforming a plurality of pores in a region consisting of aluminum, eachpore extending in a first direction from a first surface of the regiontowards a second surface opposite the first surface. Alumina can extendalong a wall of each pore, the forming performed such that portions ofthe region remain as a plurality of electrically conductive connectionelements extending in the first direction, the connection elementsconsisting essentially of aluminum and being electrically isolated fromone another by at least the alumina extending along the walls of thepores. The method may include forming a first conductive path at thefirst surface for connection with a first component external to theinterposer. The method may include forming a second conductive path atthe second surface for connection with a second component external tothe interposer. In one example, the first and second conductive pathsmay be electrically connected through at least some of the connectionelements.

In one embodiment, the first and second conductive paths may be at leastone of a plurality of contacts or a redistribution layer (RDL).

In one embodiment, each pore may have a diameter of less than 2micrometers.

In one embodiment, forming the first conductive path may compriseforming a plurality of first contacts adjacent to the first surface forconnection with a first component external to the interposer.

In one embodiment, forming the second conductive path may compriseforming a plurality of second contacts adjacent to the second surfacefor connection with a second component external to the interposer. Inone example, at least some of the first contacts may be electricallyconnected with at least some corresponding second contacts through theconnection elements.

In one embodiment, the method comprises partially or fully filling atleast some of the pores with a material.

In one embodiment, the material used to partially or fully fill the atleast some pores may be at least one of a conductive or dielectricmaterial.

In one embodiment, a method of fabricating an interposer comprisesforming a plurality of pores in a region consisting of aluminum, eachpore extending in a first direction from a first surface of the regiontowards a second surface opposite the first surface. Alumina can extendalong a wall of each pore. The method can include forming a plurality ofelectrically conductive connection elements extending in the firstdirection by at least partially filling some of the plurality of poreswith a conductive material, the connection elements being electricallyisolated from one another by at least the alumina extending along thewalls of the pores. The method can include forming a first conductivepath at the first surface for connection with a first component externalto the interposer. The method can include forming a second conductivepath at the second surface for connection with a second componentexternal to the interposer. In one example, the first and secondconductive paths may be electrically connected through at least some ofthe connection elements.

In one embodiment, each pore can have a diameter of less than 2micrometers.

In one embodiment, the first and second conductive paths may be at leastone of a plurality of contacts or a redistribution layer (RDL).

In one embodiment, forming the first conductive path may compriseforming a plurality of first contacts adjacent to the first surface forconnection with a first component external to the interposer.

In one embodiment, forming the second conductive path may compriseforming a plurality of second contacts adjacent to the second surfacefor connection with a second component external to the interposer. Inone example, at least some of the first contacts may be electricallyconnected with at least some corresponding second contacts through theconnection elements.

In one embodiment, the method may comprise partially or fully filling atleast some of the remaining pores with a material, wherein the at leastsome of the pores do not include a conductive element formed therein.

In one embodiment, the material used to partially or fully fill the atleast some remaining pores may be at least one of a conductive ordielectric material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1-1 depicts a side schematic view of a microelectronic assembly inaccordance with some embodiments of the present invention.

FIG. 1-2 depicts a side schematic view of a microelectronic assembly inaccordance with some embodiments of the present invention.

FIG. 1-3 depicts a side schematic view of a microelectronic assembly inaccordance with some embodiments of the present invention.

FIG. 1-4 depicts a top down schematic view of a microelectronic assemblyin accordance with some embodiments of the present invention.

FIG. 2-1 depicts a side schematic view of a template comprising porousalumina in accordance with some embodiments of the present invention.

FIG. 2-2 depicts a top down cross sectional view of a templatecomprising porous alumina in accordance with some embodiments of thepresent invention.

FIG. 2-3 depicts a top down cross sectional view of a templatecomprising porous alumina in accordance with some embodiments of thepresent invention.

FIG. 2-4 depicts an interposer in accordance with some embodiments ofthe present invention.

FIG. 2-5 depicts a top down view of an interposer in accordance withsome embodiments of the present invention.

FIG. 3-1 depicts a side schematic view of a template comprising porousalumina in accordance with some embodiments of the present invention.

FIG. 3-2 depicts a side schematic view of an interposer in accordancewith some embodiments of the present invention.

FIG. 3-3 depicts a top down cross sectional view of an interposer inaccordance with some embodiments of the present invention.

DETAILED DESCRIPTION

Interposers and methods of making the same are disclosed herein.Specifically, an interposer and a method of making an interposer aredescribed herein which incorporates porous alumina, e.g., a regionhaving first and second oppositely facing surfaces and a plurality ofpores, each pore extending in a first direction from the first surfacetowards the second surface and having alumina extending along the wallsof the pores. Some embodiments provide interposers in which verticalinterconnects therein may, in some examples, have aspect ratios greaterthan 5:1 and in some examples be greater than 10:1. Some embodiments mayadvantageously provide methods for making interposers that reduce thenumber of process steps, for example, such eliminating one or more ofdielectric, barrier, seed, or metal deposition.

FIGS. 1-1 to 1-4 depict various embodiments of a microelectronicassembly including an interposer. For example, an interposer may havevarious forms, such as having a continuous surface 104 extending inlateral directions 140, 142, as depicted in FIGS. 1-1 and 1-2, 140 beingin a direction depicted in the sectional view shown and 142 being in adirection along surface 104 but out of the plane of the depicted view.Alternatively, an interposer may include a frame region having a centralaperture, such as depicted in FIG. 1-3 and FIG. 1-4. Other and furtherembodiments microelectronic assemblies including interposer, inadditional to the exemplary embodiments depicted in FIGS. 1-1 to 1-3 arepossible.

FIG. 1-1 depicts a microelectronic assembly 100 having an interposer 102in accordance with some embodiments of the present invention. Theinterposer 102 may have first and second oppositely facing surfaces 104,106, e.g., top and bottom surfaces, at which first and second contacts105, 107, are exposed, respectively, for electrical connection withfirst and second components of the microelectronic assembly 100,respectively. As shown in FIG. 1-1, the first component can be acomponent having active circuit elements thereon, such as amicroelectronic element 108, for example, and the component may have aface facing towards the first surface 104 of the interposer 102 at afirst side thereof and connected to the first contacts 105 of theinterposer 102. In one example, the microelectronic element 108 can be apackaged or unpackaged semiconductor die. As further shown in FIG. 1-1,the second contacts 107 of the interposer 102 can be electricallyconnected with corresponding contacts of another component of theassembly, such as a package substrate 110 in the example illustrated inFIG. 1-1. Connection elements 111 between the first and second contacts105, 107 are provided and extend in a direction of a thickness of theinterposer between the first and second surfaces 104, 106 of theinterposer 102.

As an alternative to that shown in FIG. 1-1 or in addition thereto, someor all of the second contacts 107 may be connected with a secondmicroelectronic element, which can be an unpackaged or packagedsemiconductor die having a surface facing the second surface 106 of theinterposer 102. The package substrate 110 or other componentinterconnected with the interposer 102 can, in turn be mounted tocontacts of a circuit panel 112, as shown in FIG. 1-1.

FIG. 1-2 illustrates a microelectronic assembly 120 according to afurther example in which first and second microelectronic elements 122,124 can be electrically interconnected with an interposer 126 throughfirst contacts 105 exposed at a first surface 128 of the interposer 126.The microelectronic elements 122, 124, which may be packaged orunpackaged, may be electrically interconnected with one another throughconductive structure provided on the interposer, such as traces 130thereon, which may extend in a direction parallel to the first andsecond surfaces 128, 129 of the interposer 126. In some cases, thetraces 130 may overlie one or both of the first and second surfaces 128,129, or may be partially or fully embedded within dielectric material atone or both surfaces. In one example, as shown in FIG. 1-2, an assemblyincluding multiple microelectronic elements, which can be electricallyinterconnected with interposer 126 through first contacts 105, and maybe further electrically interconnected with each other through traces130.

FIG. 1-3 illustrates a microelectronic assembly 150 according to afurther example in which vertically stacked, first and second packagesubstrates 151, 152 having microelectronic element 154, 156,respectively disposed thereon, can be electrically interconnected withan interposer 158. As shown in FIGS. 1-3 and 1-4, the interposer 158 mayhave a frame region 159 or peripheral region that surrounds an aperture160. The frame region may 159 may overly a first surface 153 of thefirst package substrate 151, the microelectronic element 154electrically connected to the first package substrate 151 at the firstsurface 153. As shown in FIG. 1-3, the microelectronic element 154 canextend at least partly within aperture 160. The frame region may includefirst and second oppositely facing surfaces 162, 164 at which first andsecond contacts 166, 168 are respectively exposed. Connection elements170 between the first and second contacts 162, 164 are provided andextend in a direction of a thickness of the frame region 159 between thefirst and second surfaces 162, 164. The first package substrate 151 maybe electrically connected to the interposer 158 through the secondcontacts 107 at the second surface 164 of the frame region 159. Thesecond package substrate 152 may be electrically connect to theinterposer 158 through the first contacts 166 at the first surface 162of the frame region 159. The second package substrate 152 may overly thefirst surface 162 of the frame region 159 and the central aperture 160.In one embodiment, the second package substrate 152 may be substantiallysimilar to the first package substrate 151, the second package substrate152 having the semiconductor die 156 electrically connected to thesecond package substrate 152 at a first surface 155 thereof.Alternatively, configurations and/or components of the packagesubstrates 151, 152 may be different, or one or more additionalcomponents, such as an additional package substrate overlying packagesubstrate 152 may be different from package substrates 151, 152.

FIG. 2 depicts an interposer in accordance with some embodiments of thepresent invention. As shown in FIG. 2-1, an interposer may be formedhaving a structure that includes aluminum and porous alumina. At thestage of processing illustrated in FIG. 2-1, a structure 200 may includefirst and second oppositely facing surfaces 202, 204 and a plurality ofpores 206, each pore 206 extending in a first direction from the firstsurface 202 towards the second surface 204 wherein alumina 205 extendsalong a wall of each pore 206. As used herein, the term ‘pore’ means anopening that results from a process of oxidizing an aluminum region orlayer, the process converting the aluminum (Al) along the walls of theopenings into alumina (Al₂O₃). The process can be conducted such thatthe pores are sufficiently close to each other to cause the aluminaregions that form along the walls of directly adjacent pores to mergetogether in one electrically isolating region. In one embodiment, asillustrated in FIG. 2-1, walls 207 of directly adjacent pores 206 canconsist essentially of alumina. In one embodiment, walls of adjacentpores may include aluminum, where the aluminum is encompassed by thealumina 205 extending along the walls of each pore or otherwiseisolated, such that it does not form an electrical connection with theconnection elements 208 discussed below. The process is typicallyconducted such that each pore may have a diameter of less than about 2micrometers, and which may be substantially smaller, e.g., ranging fromabout 100 nanometers to about two micrometers.

As shown in FIG. 2-1, the structure 200 may include a plurality ofelectrically conductive connection elements 208 extending in the firstdirection. The connection elements 208 may consist essentially ofaluminum. The connection elements 208 may be electrically isolated fromone another by at least the alumina 205 extending along the walls of thepores 206. For example, as illustrated in top down partial cross sectionview in FIG. 2-2, the structure 200 or at least a region thereof mayconsist essentially of pores, the alumina extending along the walls ofeach pore 206. Although illustrated as having a circular cross sectionin FIG. 2-2, the connection elements 208 may have any suitable crosssection, such as non-circular, oblong, rectangular, or other suitablecross sections.

Alternatively, as illustrated in top down partial cross section view inFIG. 2-3, the structure 200 may have at least a region 211 thereofconsisting essentially of aluminum. At least some of the pores 206 maybe disposed adjacent one another in annular patterns 209, disposedwithin the surrounding region 211. In a particular example, suchaluminum region 211 can be continuous and can extend throughout the samearea that the structure 201 extends. At least some of the annularpatterns 209 encompass connection elements 208 of the plurality ofconnection elements 208 and the alumina extending along the walls of thepores 206 of the at least some annular patterns 209 electricallyisolates respective connection elements 208 from one another. Althoughillustrated as circular in FIG. 2-3, the annular pattern 209 may haveany suitable annular shape, such as non-circular, oblong, rectangular,or the like. Although illustrated as a single layer of pores 206 in FIG.2-3, the annular pattern 209 may include one or more layers ofalumina-containing pores 206 surrounding each connection element 208 indirections parallel to surfaces 202, 204 of structure 200.

The interposer of the present invention may have a heat spreaderfunction. In one embodiment, a region consisting essentially ofaluminum, such as illustrated in FIG. 2-3, surrounding at least some ofthe connection elements 208 may be configured to provide the heatspreader function. An interposer of the present invention may includeboth embodiments as illustrated in FIGS. 2-2 and 2-3, or alternatively,a combination of the concepts from each embodiment. For example, asillustrated in FIG. 2-2, a region 210 consisting essentially of aluminummay be surrounding at least one or more connection elements 208. Region210 can be disposed within a porous alumina region. The region 210 mayprovide a heat spreader function to an interposer of the presentinvention. The surrounding region 211 of aluminum seen in FIG. 2-3 canserve as a heat spreader in an interposer made from structure 200.

The structure 200 may be formed by a low cost, anodization process thatcan produce regular and anisotropic pores. In one embodiment, poredensity may range from about 10⁶ to about 10¹² per square centimeter(cm²). In some embodiments, pores can be uniformly distributed and/ordisordered in accordance with a desired pore diameter.

An exemplary method of fabricating the structure 200 can includeelectro-polishing a surface of a substrate consisting essentially ofaluminum. Electro-polishing may be utilized to reduce surface roughnessto about 100 nanometers or less. In one embodiment, to form thestructure 200 illustrated in FIG. 2-2, a patterned mask layer may beapplied to the electro-polished surface, the patterned mask layeroverlying regions of the electro-polished surface where aluminum is tobe preserved, such as the connection elements 208 and/or the region 210and/or the aluminum regions 208, 211 as illustrated in FIG. 2-3. Thesubstrate may then be electrolyzed using a acid solution, such as havinga pH of less than about 5 to form the structure 200. One or more processvariations may be possible, such as multi-step anodization processes toimprove pore uniformity. A more complete description of anodizationprocesses for forming a structure comprising porous alumina can be foundin S. Bandyopadhyay et al., Nanotechnology, Vol. 7, 1996, which isincorporated herein by reference.

After formation of the structure 200, an interposer 212 may be formedfrom the structure 200. The interposer 212 is illustrated in FIG. 2-4.The interposer 212 may include a first conductive path 213 provided atthe first surface 202 for connection with a first component external tothe interposer 212. The interposer 212 may include a second conductivepath 231 provided at the second surface 204. As shown in FIG. 2-4, thesecond surface 204 may be thinned until alumina at bottoms of pores 206is exposed, prior to forming the second conductive path 231, asdiscussed herein. The first and second conductive paths 213, 231 mayinclude any suitable components and/or methods known in the art, such asone or more of contacts, traces, micro vias, or the like. The first andsecond conductive paths may be included as part of one or more of aredistribution layer (RDL), a back end of line (BEOL) layer, or thelike. It will be understood that an RDL and/or BEOL layer can includemultiple layers. Further, although illustrated as having differentstructures in the interposer 212, the first and second paths 213 and 231can be the same or different. The first and second conductive paths 213,231 can include components formed from one or more of aluminum (Al),copper (Cu), alloys thereof, or other conductors.

The first conductive path 213 may include a plurality of first contacts214 at the first surface 202 for connection with a first componentexternal to the interposer 212. At least some of the first contacts 214can be electrically connected with connection elements 208, eitherdirectly and extend through a dielectric region 218, or through elementsextending through the dielectric region 218. The dielectric region 218and the first contacts 214 may be formed by any suitable and dielectricprocessing. As used in this disclosure with reference to a substrate, astatement that an electrically conductive element is “at” a surface of asubstrate indicates that, when the substrate is not assembled with anyother element, the electrically conductive element is available forcontact with a theoretical point moving in a direction perpendicular tothe surface of the substrate toward the surface of the substrate fromoutside the substrate. Thus, a terminal or other conductive elementwhich is at a surface of a substrate may project from such surface; maybe flush with such surface; or may be recessed relative to such surfacein a hole or depression in the substrate.

As seen in FIG. 2-4, the dielectric region 218 may overlie or cap thepores 206. In one embodiment, as illustrated in FIG. 2-4, at least someof the pores 206 may be at least partially filled with a material 226.In one embodiment, the material 226 may be residual dielectric materialresulting from deposition of the dielectric region 218. In oneembodiment, the material 226 may be a non-conductive material, such as adielectric material that may be the same as the dielectric material ofthe dielectric region 218 or a different dielectric material. In oneembodiment, the material may be an electrically conductive material thatmay be used for heat spreader functions in the interposer 212. When atleast some of the pores 206 are partially filled by the material 226 ornot filled at all, the pores may incorporate voids. Alternatively, or incombination with, at least some of the pores 206 may be completelyfilled with the material 226.

The first contacts 214 may have various configurations at the firstsurface 202, and/or at a first surface 220 of the dielectric region 218as illustrated in top down view of the interposer 212 in FIGS. 2-4 and2-5. The first contacts may be aligned with, overlying, and/or notoverlying the connection elements 208 and/or pores 206. For example, asolder ball 215 may be attached to one or more first contacts 214 whichmay be overlying a single connection element 208 or spanning adjacentconnection elements 208. The first contact 214 may be a pad, overlying aconnection element 208 or not overlying a connection element 208, suchas electrically connected to a trace 224 that may extend along the firstsurface 220 of the dielectric element from a position overlying oradjacent to a connection element 208. The first contacts 214 may overliesome of the pores 206 or the connection elements 208. In one embodiment,at least some of the first contacts overlie some of the pores 206. Inone embodiment, at least some of the first contacts 214 overlie theconnection elements 208. In one embodiment, there can be first contacts214 which do not overlie the connection elements 208.

The first contacts 214 may be electrically connected to at least oneconnection element 208 by at least one joining element 228 which mayinclude a trace, via or combination thereof. For example, each joiningelement 228 may be disposed atop a corresponding connection element 208at the first surface 202. The joining element may be of one or moresuitable electrically conductive materials, such as a metal, aconductive compound of a metal, or a conductive material within apolymer matrix, for example.

The second conductive path 231 may include a plurality of secondcontacts 216 at the second surface 204 of the interposer 212. The secondcontacts 216 may have any suitable configuration, such as any of thoseconfigurations discussed above in accordance with the first contacts214. The second contacts 216 can extend through a dielectric region 232overlying the second surface 204, and/or be arranged at an exposedsurface 230 of the dielectric region 232. As illustrated in FIG. 2-4, atleast some of the first contacts 214 may be electrically connected withat least some corresponding second contacts 216 through the connectionelements 208.

As shown in FIG. 2-4, the structure can be thinned from the secondsurface 204 until alumina at bottoms of pores 206 is exposed at thesecond surface 204. In one embodiment, the alumina can be used as apolish stop and an end point during removal of the material from thesecond surface 204. Similar to the first contacts 214, the secondcontacts 216 may be electrically connected to at least one connectionelement 208 or spanning adjacent connection elements 208, or connectedto at least one connection element 208 by a joining element, such as atrace or the like. For example, a solder ball 217 may be attached to atleast one second contacts 216 which may be overlying a single connectionelement 208.

Alternatively, or in combination with the interposer 212, otherembodiments of an interposer using a structure comprising porous aluminaare possible. For example, FIG. 3-1 illustrates a structure 300comprising porous alumina. Where the template 300 has overlappingfeatures with the structure 200, the same number labels are used. Thestructure 300 may include first and second oppositely facing surfaces302, 304 and the plurality of pores 206, each pore 206 extending in afirst direction from the first surface 302 towards the second surface304 wherein alumina 205 extends along a wall of each pore 206. In oneembodiment, as illustrated in FIG. 3-1, walls 207 of directly adjacentpores 206 can consist essentially of alumina. In one embodiment, wallsof adjacent pores may include aluminum, where the aluminum isencompassed by the alumina 205 extending along the walls of each pore orotherwise isolated, such that it does not form an electrical connectionwith the connection elements 306 discussed below. Unlike the structure200, which includes connection elements 308 integrated therewith, thestructure 300 consists essentially of pores 206, and may have a base 301consisting essentially of aluminum at the second surface 304.

An exemplary method of fabricating the structure 300 is similar to themethod discussed above for forming the structure 200, except nopatterned mask layer is used and connection elements are not formed as aresult of the fabrication process.

After formation of the structure 300, an interposer 308 may be formedfrom the structure 300. The interposer 308 is illustrated in FIG. 3-2.The interposer 308 may include a plurality of connection elements 310extending in the first direction by at least partially filling some ofthe plurality of pores with a conductive material. Each connectionelement 310 may comprise the conductive material at least partiallyfilling one pore 206. The connection elements 310 may be electricallyisolated from one another by at least the alumina extending along thewalls of each pore 206. As depicted in FIG. 3-2 and in top down crosssection view in FIG. 3-3 the connection elements 310 can be clustered inadjacent pores 206, for example, such as to for vias or otherinterconnect structures. This clustering of connection elements 310 ismerely exemplary, and other configurations of the connection elements310 within the interposer 308 are possible. For example, some connectionelements 310 can occupies an area of the first surface 202 whichencompasses areas occupied by others of the connection elements 310,such as in an embodiment similar to region 210. The some connectionelements 310 can be configured as a heat spreader of the interposer.

As shown in FIG. 3-2, the interposer 308 may include first and secondconductive paths 213, 231 similar to those described above relative toFIG. 2-4, and conductive elements connecting them with connectionelements 310. The first and second conductive paths 213, 231 can includefirst contacts 214 and second contacts 216 similar to those describedabove relative to FIG. 2-4.

The dielectric region 218 shown in FIG. 3-2 may overlie or cap the pores206. In one embodiment, as illustrated in FIG. 3-2, at least some of theremaining pores 206, such as those pores 206 not used to form connectionelements 310, may be at least partially filled with a material 226 suchas described above relative to FIG. 2-4.

As illustrated in FIG. 3-2, contacts 214 or contacts 216 can beelectrically connected to several connection elements 310, which areformed in a cluster.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

The invention claimed is:
 1. An interposer, comprising: a region having first and second oppositely facing surfaces and a plurality of pores, each pore extending in a first direction from the first surface towards the second surface, wherein alumina extends along a wall of each pore; a plurality of electrically conductive connection elements extending in the first direction, the connection elements consisting essentially of aluminum and being electrically isolated from one another by at least the alumina extending along the walls of the pores; a first conductive path provided at the first surface for connection with a first component external to the interposer; and a second conductive path provided at the second surface for connection with a second component external to the interposer, wherein the first and second conductive paths are electrically connected through at least some of the connection elements, and wherein at least some of the pores are disposed adjacent one another in annular patterns, and at least some of the annular patterns encompass connection elements of the plurality of connection elements and the alumina extending along the walls of the pores of the at least some annular patterns electrically isolates respective connection elements from one another.
 2. The interposer of claim 1, wherein each pore has a diameter of less than about 2 micrometers.
 3. The interposer of claim 1, wherein the first and second conductive paths are at least one of a plurality of contacts or a redistribution layer (RDL).
 4. The interposer of claim 1, wherein the first conductive path further comprises: a plurality of first contacts adjacent to the first surface for connection with a first component external to the interposer; and wherein the second conductive path further comprises: a plurality of second contacts adjacent to the second surface for connection with a second component external to the interposer, wherein at least some of the first contacts are electrically connected with at least some corresponding second contacts through the connection elements.
 5. The interposer of claim 1, wherein at least a portion of the interposer has a heat spreader function.
 6. The interposer of claim 1, wherein the aluminum region surrounding the at least some of the connection elements is configured to provide a heat spreader function.
 7. The interposer of claim 1, wherein at least a portion of the first conductive path overlies some of the pores.
 8. The interposer of claim 7, wherein no part of the at least a portion of the first conductive path overlies the connection elements.
 9. The interposer of claim 1, wherein at least a portion of the first conductive path is aligned with the connection elements.
 10. The interposer of claim 1, wherein at least some of the pores incorporate voids.
 11. The interposer of claim 1, wherein at least one connection element occupies an area of the first surface which encompasses areas occupied by others of the connection elements, the at least one connection element configured as a heat spreader of the interposer.
 12. The interposer of claim 1, wherein at least some of the pores are at least partially filled with a dielectric material overlying the alumina.
 13. The interposer of claim 1, wherein at least some of the pores are at least partially filled with an electrically conductive material.
 14. The interposer of claim 1, further comprising: second connection elements extending in the first direction, each second connection element comprising an electrically conductive material extending within some of the plurality of pores, at least some of the first contacts being electrically connected with corresponding second contacts through the second connection elements.
 15. A method of fabricating an interposer, comprising: forming a plurality of pores in a region consisting of aluminum, each pore extending in a first direction from a first surface of the region towards a second surface opposite the first surface, and having alumina extending along a wall of each pore, the forming performed such that portions of the region remain as a plurality of electrically conductive connection elements extending in the first direction, the connection elements consisting essentially of aluminum and being electrically isolated from one another by at least the alumina extending along the walls of the pores; wherein at least some of the pores are disposed adjacent one another in annular patterns, and at least some of the annular patterns encompass connection elements of the plurality of connection elements; forming a first conductive path at the first surface for connection with a first component external to the interposer; and forming a second conductive path at the second surface for connection with a second component external to the interposer, wherein the first and second conductive paths are electrically connected through at least some of the connection elements.
 16. The method of claim 15, wherein the first and second conductive paths are at least one of a plurality of contacts or a redistribution layer (RDL).
 17. The method of claim 15, wherein each pore has a diameter of less than 2 micrometers.
 18. The method of claim 15, wherein forming the first conductive path further comprises: forming a plurality of first contacts adjacent to the first surface for connection with a first component external to the interposer; and wherein forming the second conductive path further comprises: forming a plurality of second contacts adjacent to the second surface for connection with a second component external to the interposer, wherein at least some of the first contacts are electrically connected with at least some corresponding second contacts through the connection elements.
 19. The method of claim 15, further comprising: partially or fully filling at least some of the pores with a material.
 20. The method of claim 19, wherein the material used to partially or fully fill the at least some pores is at least one of a conductive or dielectric material.
 21. An interposer, comprising: a region having first and second oppositely facing surfaces and a plurality of pores, each pore extending in a first direction from the first surface towards the second surface, wherein alumina extends along a wall of each pore; a plurality of electrically conductive connection elements extending in the first direction, the connection elements consisting essentially of aluminum and having at least a portion disposed outside of the interior volume of any individual pore, the connection elements electrically isolated from one another by at least the alumina extending along the walls of the pores; a first conductive path provided at the first surface for connection with a first component external to the interposer; and a second conductive path provided at the second surface for connection with a second component external to the interposer, wherein the first and second conductive paths are electrically connected through at least some of the connection elements, and at least some of the pores are disposed adjacent one another such that regions of the alumina which extend along the walls of directly adjacent pores are merged together in a common electrically isolating region surrounding and electrically isolating each of a plurality of the electrically conductive connection elements from one another.
 22. The interposer of claim 21, wherein at least some of the electrically conductive connection elements are disposed entirely outside of internal volumes defined by the alumina extending along the walls of the pores.
 23. The interposer of claim 21, wherein each pore has a diameter of less than about 2 micrometers.
 24. The interposer of claim 21, wherein the first and second conductive paths are at least one of a plurality of contacts or a redistribution layer (RDL).
 25. The interposer of claim 21, wherein the first conductive path further comprises: a plurality of first contacts adjacent to the first surface for connection with a first component external to the interposer; and wherein the second conductive path further comprises: a plurality of second contacts adjacent to the second surface for connection with a second component external to the interposer, wherein at least some of the first contacts are electrically connected with at least some corresponding second contacts through the connection elements.
 26. The interposer of claim 21, wherein at least a portion of the interposer has a heat spreader function.
 27. The interposer of claim 21, wherein the aluminum region surrounding the at least some of the connection elements is configured to provide a heat spreader function.
 28. The interposer of claim 21, wherein at least one connection element occupies an area of the first surface which encompasses areas occupied by others of the connection elements, the at least one connection element configured as a heat spreader of the interposer.
 29. The interposer of claim 21, wherein at least some of the pores are at least partially filled with a dielectric material overlying the alumina.
 30. The interposer of claim 21, wherein at least some of the pores are at least partially filled with an electrically conductive material. 